A study is being made of the response properties of individual neurons and of large groups of neurons in the mammalian somatosensory system to various cutaneous stimuli. The gross voltage changes (evoked potentials) and patterns of current flow produced by activity in these neurons is also under study. By extracellular recording, neurons are classified into different functional sets on the basis of their natural stimulus sensitivities, excitatory receptive field sizes, site(s) of projection of their axons, and response properties to electrical stimulation at the center of their cutaneous excitatory receptive fields. Because it is technically impossible to demonstrate synaptic connections among members of the various functional sets directly, possible connections are deduced through study and comparison of the overall patterns of response of members of the various functional sets. The techniques being developed to find these interconnections involve acquisition and processing of large numbers of observations on large numbers of individual neurons gathered at known sites in the nervous system. To aid in attaining the above objectives, a fully automated research facility is under development. Using a computer-controlled microdrive system, neurons responsive to the hunting stimulus are automatically detected, isolated and identified, and a predefined, dynamically altering, experiment is then performed on each neuron. Appropriate stimuli are delivered under computer command, data are acquired by the computer and immediately analyzed. Full development of the technique should increase the data yield per animal five- to tenfold, with a uniform rather than varying sampling bias.